Set-screw type terminal connector lug



Jan. 5, 1960 H. B. GIBSON ET AL 2,920,305

SET-SCREW TYPE TERMINAL CONNECTOR we Filed April 4, 1957 AZ INVENTORSflan A20 5. 6/550 flag Aka 6. 7oq=k ATTORNEY United States PatentSET-SCREW TYPE TERMINAL CONNECTOR LUG Howard B. Gibson, Glen Ridge, andHoward G. Tomer, North Arlington, N.J., assignors to The Thomas & BettsCo., Elizabeth, NJ., a corporation of New Jersey Application April 4,1957, Serial No. 650,595

9 Claims. (Cl. 339-272) The invention relates to electric terminalconnectors of the heavy duty, set-screw type, adapted for detachablyconnecting thereto any one of a plurality of multistrand cableconductors having different circular mil areas, and more particularly toa terminal connector of the character wherein the set-screw coacts, indiiferent positions of adjustment, with the body of the terminalconnector to provide a gage whereby a predetermined compressive bindingforce may be applied on a cable able tool connecting or receiving meanssurrounded by a plurality of stepped plane segmental surfaces adapted tobe selectively aligned flush'with said barrel portion, in accordancewith the circular mil area of the cable conductor end portion to besecured therein by said set-screw.

Electric terminal connectors of the set-screw type, as known heretofore,were subject to certain disadvantages in that a cable conductor wasintruded into a circular bore, and the set-screw secured thereon withrandom compressive force, whereby the intruded portion of the conductorwas subjected to an indefinite amount of deformation and often withseverance of at least some of the conductor strands. Thus, a goodmechanical connection was not practical, relative movement therebetweenunavoidable, and maximum current-carrying capacity of the cableconductor more or less impaired.

Accordingly, it is an object of the invention to provide an improvedterminal lug connector of the setscrew type which is not subject to theabove-noted disadvantages. 1

A further object of the invention is to provide a terminal lug connectoras specified, wherein the set-screw for securing a multi-strand cableconductor therein, is adapted for obviating transverse resistancebetween the inner and outer strands thereof at its secured end portion.

Another object of the invention is to provide a terminal lug connectoras specified, wherein the set-screw includes gage means coactable withthe body of the connector, whereby predetermined amounts of compressionmay be selectively applied on cable conductors of different circular milarea. 7

A further object of the invention is to provide a terminal lug connectoras specified, whereby the set-screw is secured upon the intruded portionof a cable conductor in accordance with a predetermined amount ofcompressive force for a cable conductor having a given circular milarea.

Another object of the invention is to provide a terminal lug connectoras specified, wherein the conductorreceiving bore in the barrel portionof the lug is adapted to align cable conductors of varying circular milarea with the axial center of the set-screw 24, whereby the entirebearing end face of the set-screw is brought into intimate engagementsquare therewith in response to a predetermined amount of compressionapplied thereon by said set-screw.

'A further object of the invention is to provide a terminal lugconnector as specified which is particularly adapted for eifecting goodinternal and external mechanical and electrical contact with cableconductors having a relatively small circular mil area, as well as cableconductors having a larger circular mil area.

With the above and other objects in view, the inven; tion resides inthenovel construction, combination, and arrangement of parts, the novelfeatures of which are set forth with particularity in the appendedclaims. The invention, both as to its organization and method ofconstruction, together with additional objects and advantages thereof,will be understood from the following description of a specificembodiment, when taken in connection with the accompanying drawing, inwhich:

Fig. 1 is a view in perspective showing the improved terminal lugconnector;

Fig. 2 is a top plan view of the improved terminal lug connector;

Fig. 3 is an end elevation of the terminal lug connector showing thenon-circular bore in the conductorreceiving end thereof;

Fig. 4 is a longitudinal sectional view taken on the line 44 of Fig. 2;and

Fig. 5 is a transverse sectional view of the conductorreceiving endportion of the terminal connector and showing the set-screw more or lessin an initial position on the intruded portion of a cable conductor.

Referring to the drawing, the improved terminal lug connector, ofaluminum, bronze, or copper, for example, indicated generally at 10,comprises a flat tongue portion 12, provided with the usual aperture '14for receiving a terminal stud or the like therethrough, a substantiallyrectangular barrel portion 16 provided with a circular or non-circularbore 18 adapted for the intrusion therein of an end portion of amulti-strand cable conductor 20, and a screw-threaded bore 22 normalthereto, for the reception of a set-screw 24 of compatible metal orequivalent, adapted for securing the cable conductor 20 to the terminalconnector lug 10.

In accordance with the invention, the set-screw 24 of the headless typehaving either a V screw thread or a buttress screw thread 25, formedthereon, is provided with a bearing end face in the form of a flat,annular bearing face 26, square therewith, and a conical tip 28, havinga blunt or rounded apex portion 30, depending therefrom in concentricrelation and defining a continuation of the surface of the fiat annularface 26, whereby the set-screw is adapted for limited penetration of theintruded end portion of the multi-strand cable 20, to establish goodmechanical and electrical contact with its inner strands, to obviatetransverse resistance therebetween, and to clamp down on the outerstrands engaged by its fiat bearing face 26, to lock the set screw inpredetermined positions of adjustment.

The opposite or outer end face of the set-screw 24 is provided with acentral, hexagonal recess 32, for example, for the insertion therein ofan Allen wrench for manipulating the setscrew relative to the connectorlug 10, in known manner.

Further in accordance with the invention, the recessed opposite end faceof the set-screw 24 is formed to present a plurality of stepped surfaces34 arranged in angular relation about the hexagonal recess 32 and offsetfrom each other in the direction of the axis of the set-screw 24, eachin a plane perpendicular thereto, whereby, when the set-screw 24 isrotated clockwise onto a selected cable conductor having a predeterminedcircular mil area, one of the stepped gaging surfaces 34, correspondingthereto, will register flush with the top side of the barrel portion 16,of the terminal connector lug 1i and thus indi cate that the appropriatecompressive binding force for securing the selected size of cableconductor has been applied thereon, each of the stepped gage surfaces 34being provided with suitable indicia, as at 36, for example, to identifythe particular gage surface 34 for the corresponding size of cableconductor secured in the terminal connector. An example of such indicia36 comprises American wire gage numbers designating 2/0, 3/0, 4/0 and250 thousand circular mil cable conductor sizes for use with theterminal connector illustrated.

Further in accordance with the invention, the bore 18 in the terminallug 18 is of substantially egg-shaped or inverted tear-dropconfiguration in outline by reason of its lower or bottom half having arelatively smaller radius than that of its upper half, whereby to assuremaximum contact with small as well as larger size multi-strandconductors, and also for more effectively compacting the intruded endportion thereof in substantially wedge-like fashion, in response to theentire bearing end face of the set-screw 24, when turned down thereon.

Referring to Figs. 3 and 4, the screw-threaded bore 22 intersects therelatively smaller conductor-receiving bore 18 at right angles thereto,whereby the incursion there of into the side Walls of the bore 18 formsoppositely disposed arcuate steps or shoulders 33 therein with thedefining surfaces thereof inclined downwardly toward the bottom or floor49 thereof, to provide clearance for the lateral spread of a portion ofthe outer strands of the intruded conductor 20, into the path of thefiat, annular bearing face 26 of the set-screw 24, and for clamping thestrands of the intruded conductor portion down on the steps or shoulders38, and on the bottom or floor 49 of the bore 18, in response to thepenetration of the conical tip portion 28 of the set-screw 24 into theintruded conductor portion 2%, whereby a greater area of contact betweenthe entire bearing end of the set-screw 24 and the intruded conductorportion 29 is possible and the setscrew 24 caused to bottom thereon bythe clamping action of its flat, annular bearing face 26, and thussecured against relative movement.

Referring to Fig. 5, it will be apparent that when a bare end portion ofa multi-strand conductor of predetermined circular mil area is intrudedinto the bore 18 of the terminal lug 1i and the set-screw 24 initiallyturned down thereon, the conical tip portion 28 thereof penetrates andspreads the strands thereof more or less, de pending on its circular milarea, substantially laterally in opposite directions toward and over therespective steps or shoulders 38, where they are engaged by the flat, annular bearing face 26 of the set-screw 24 as it is turned down furtherto exert a predetermined amount of compression thereon in accordancewith its circular mil area, to secure the conductor 2b to the terminallug it and at the same time lock the set-screw 24 against relativemovement, as will be understood.

From the foregoing, it will be readily apparent that the presentinvention provides an improved mechanical and electrical connectionbetween a terminal connector lug of the set-screw type and amulti-strand cable conductor by reason of a larger area of contactbetween the setscrew 24- and the cable conductor a connection in whichthe strands, at the intruded end portion of the conductor, are notdamaged or impaired; a connection which obviates relative movementduring the manipulation of the cable conductor and/ or terminal lug, asin the installation thereof or subsequent thereto, and a connectionwhich obviates transverse resistance between the strands of the securedend portion of the conductor.

While the invention has been illustrated and described with respect to apreferred embodiment thereof, it is to be expressly understood thatvarious changes, modifications and substitutions in the material and/orconstruction of the improved terminal lug connector may be made withoutdeparting from the inventive concept un derlying the same. Therefore,the invention is not to be limited except as is necessitated by theprior art and the scope of the appended claims.

We claim:

1. A terminal connector lug, for cable conductors of different circularmil area, including a substantially rectangular body portion having acable conductor-receiving bore therein, adjustable means carried by saidbody portion in intersecting relation with said bore including bearingmeans adapted for respectively penetrating and clamping a conductor endportion in said bore, and stepped gaging means formed on said adjustablemeans adapted to be selectively brought into register with the adjacentsurface of said body portion whereby to indicate a predeterminedadjustment thereof in accordance with the circular mil area of aselected cable conductor.

2. A terminal connector lug, for multi-strand cable conductors,including a substantially rectangular body portion provided with anaxial bore adapted for the reception of cable conductors havingdifferent circular mil areas, adjustable means carried by said bodyportion in intersecting relation with said bore including bearing meansadapted for respectively penetrating and clamping a conductor endportion in said bore, a wrench receiving means integral with saidadjustable means, and stepped gaging means formed on said adjustablemeans adapted to be selectively brought into registration with one faceof said body portion for indicating a predetermined adjustment of saidadjustable means in accordance with the circular mil area of a selectedcable conductor.

3. A terminal connector lug, for cable conductors of different circularmil area, including a substantially rectangular body portion having anon-circular axial bore adapted for the intrusion therein of a selectedcable conductor, adjustable means carried by said body portion inintersecting relation with said bore for securing a selected cableconductor therein, and stepped gaging means integral with saidadjustable means adapted for selective registration with one face ofsaid body portion for indicating a predetermined adjustment thereof on acable conductor end portion in accordance with its circular mil area.

4. A terminal connector lug including a substantially rectangular bodyportion having a cable conductor-receiving bore therein, and a set-screwcarried by said body portion in intersecting relation with said boreincluding stepped gaging surfaces adapted to be brought intoregistration with one face of said body portion for selectivelyindicating a predetermined adjustment thereof on an end portion of acircle conductor in accordance with its circular mil area.

5. A terminal connector lug including a substantially rectangular bodyportion having an axial bore therein for freely receiving an end portionof a multi-strand cable conductor, and a set-screw carried by said bodyportion in intersecting relation with said bore for securing saidconductor end portion in said bore, said set-screw including planebearing means normal thereto adapted for clamping down on the outerstrands of said conductor end portion, conical bearing means concentricwith and depending from said clamping means adapted for limitedpenetration of said conductor end portion for effecting direct contactwith the inner strands thereof, and stepped gaging surfaces adapted tobe selectively brought into registration with one face of said bodyportion for indieating a predetermined adjustment of said set-screw on acable conductor end portion in accordance with its circular mil area.

6. A terminal connector lug, for multi-strand cable conductors ofdifferent circular mil area, including a substantially rectangular bodyportion having an axial bore therein adapted for the reception of aselected cable conductor end portion, a set-screw carried by said bodyportion in intersecting relation with said bore for securing a conductorend portion therein, conical bearing means including a straight annularshoulder normal thereto integral with said set-screw adapted forrespectively penetrating and clamping a conductor end portion in saidbore whereby to obviate transverse resistance between the inner strandsthereof and relative movement of said conductor end portion, and aplurality of stepped gaging surfaces formed on the opposite end portionof said set-screw adapted to be selectively brought into registrationwith the adjacent surface of said body portion for indicating apredetermined adjustment of said setscrew on a conductor end portion inaccordance with its circular mil area.

7. A terminal connector lug for multi-strand cable conductors ofdifferent circular mil area, including a substantially rectangular bodyportion having a non-circular axial bore therein for the reception of anend portion of a selected cable conductor, a relatively largescrewthreaded bore in said body portion opening into said noncircularbore providing oppositely disposed, inclined shoulders in the definingwall surface of the lower half of said non-circular bore, and a setscrew in said threaded bore having a bearing end comprising a conicaltip and a flat annular face about the base of said tip in concentricrelation, said conical tip being adapted for penetrating a conductor endportion to directly contact its inner strands and for spreading itsouter strands onto said shoulders, and said annular face adapted forcompacting and clamping the intruded conductor end portion on the bottomof said non-circular bore while clamping the spread strands thereof onsaid shoulders to lock said set-screw and cable conductor againstrelative movement, the op posite end of said set-screw being providedwith stepped gaging surfaces adapted for selective registration with theadjacent surface of said body portion to indicate predeterminedadjustment thereof on a cable end portion in accordance with itscircular mil area.

8. A terminal connector log, for multi-strand cable conductors ofdifferent circular mil area, including a substantially rectangular bodyportion having a non-circular axial bore therein for the reception of anend portion of a selected cable conductor, a relatively largescrewthreaded bore in said body portion opening into said noncircularbore providing oppositely disposed, downwardly inclined shoulders in thedefining wall surface of the lower half of said non-circular bore, and aset-screw in said threaded bore having a bearing end comprising aconical tip including a rounded apex portion, and a flat annular faceabout the base of said tip in concentric relation, said conical tipbeing adapted for penetrating a conductor end portion to directlycontact its inner strands and for spreading its outer strands onto saidshoulders, and said annular face adapted for compacting and clamp ingthe intruded conductor end portion on the bottom of said non-circularbore while clamping the spread strands thereof on said shoulders to locksaid set-screw and cable conductor against relative movement, theopposite end of said set-screw being provided with stepped gagingsurfaces adapted for selective registration with the adjacent surface ofsaid body portion to indicate predetermined adjustment thereof on acable end portion in accordance with its circular mil area.

9. A terminal connector lug, for multi-strand cable conductors ofdifferent circular mil area, including a substantially rectangular bodyportion having a non-circular axial bore therein for the reception of anend portion of a selected cable conductor, a relatively largescrewthreaded bore in said body portionopening into said non-circularbore providing oppositely disposed, downwardly inclined shoulders in thedefining wall surface of the lower half of said non-circular bore ofrelatively smaller radius, and a set-screw in said threaded bore havinga bearing end comprising a conical tip including a rounded apex portion,and a fiat annular face about the base of said tip in concentricrelation, said conical tip being adapted for penetrating a conductor endportion to directly contact its inner strands and for spreading itsouter strands onto said shoulders, and said annular face adapted forcompacting and clamping the intruded conductor end portion on the bottomof said noncircular bore while clamping the spread strands thereof onsaid shoulders to lock said set-screw and cable conductor againstrelative movement, the opposite end of said set-screw being providedwith stepped indicia bearing gaging surfaces adapted for selectiveregistration with the adjacent surface of said body portion to indicatepredetermined adjustment thereof on a cable end portion in accordancewith its circular mil area.

References Cited in the file of this patent UNITED STATES PATENTS411,444 Irmen Sept. 24, 1889 1,351,721 Eickhoff et a1 Aug. 31, 19202,083,923 Rowe June 15, 1934 2,232,857 Jackson Feb. 25, 1941 2,459,832McKinley Jan. 25, 1949 2,514,794 Prince July 11, 1950 2,565,140 LeustigAug. 21, 1951

